title: Reliability of corticomotor excitability in leg and thigh musculature at 14 and 28 days.
abstract: BACKGROUND
  Alterations in corticomotor excitability are observed in a variety of patient populations, including the musculature surrounding the knee and ankle after joint injury. Active motor threshold (AMT) and motor-evoked-potential (MEP) amplitudes elicited through transcranial magnetic stimulation (TMS) are outcome measures used to assess corticomotor excitability and have been deemed reliable in upper-extremity musculature. However, there are few studies assessing the reliability of TMS measures in lower-extremity musculature.
  
  
  OBJECTIVE
  To determine the intersession reliability of AMT and MEP amplitudes over 14 and 28 d in the quadriceps and fibularis longus (FL).
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  University laboratory
  
  
  METHODS
  20 able-bodied volunteers (10 men, 10 women; 22.35 ± 2.3 y, 1.71 ± 0.11 m, 73.61 ± 16.77 kg).
  
  
  METHODS
  AMT and MEP amplitudes were evaluated at 95%, 100%, 105%, 110%, 120%, 130%, and 140% of AMT in the dominant and nondominant quadriceps and FL. Interclass correlation coefficients (ICCs) were used to assess reliability for absolute agreement and internal consistency between baseline and 2 follow-up sessions at 14 and 28 d postbaseline. Each ICC was fit with the best-fit straight line or parabola to smooth out noise in the observations and best determine if a pattern existed in determining the most reliable MEP value.
  
  
  RESULTS
  All muscles yielded strong ICCs between baseline and both time points for AMT. MEPs in both the quadriceps and FL produced varying degrees of reliability, with the greatest reliability demonstrated on day 28 at 130% and 140% of AMT in the quadriceps and FL, respectively. The dominant FL muscle showed a significant pattern; as TMS intensity increased, MEP reliability increased.
  
  
  CONCLUSIONS
  TMS can be used to reliably identify corticomotor alterations after therapeutic interventions, as well as monitor disease progression.
authors.affiliation: Dept of Exercise and Sports Science, University of North Carolina at Chapel Hill, Chapel Hill, NC.
authors.forename: Brittney A
authors.initials: BA
authors.lastname: Luc
authors.forename: Adam S
authors.initials: AS
authors.lastname: Lepley
authors.forename: Michael A
authors.initials: MA
authors.lastname: Tevald
authors.forename: Phillip A
authors.initials: PA
authors.lastname: Gribble
authors.forename: Donald B
authors.initials: DB
authors.lastname: White
authors.forename: Brian G
authors.initials: BG
authors.lastname: Pietrosimone
mesh_terms: D004576:Electromyography; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D015203:Reproducibility of Results; D013848:Thigh / Q000502:physiology*; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation / Q000379:methods* / Q000592:standards; D055815:Young Adult